1. Technical Field of the Invention
The present invention relates to a hematology control product for use in automated hematology instruments using electronic, optical and absorption means. The hematology control product provides quality assurance of proper instrument operation.
2. Discussion of the Prior Art
Quality control is a necessary and routine procedure in clinical hematology. Hematology control products are widely used as a quality control material to monitor automated electronic instrument determinations of blood cell values in various established clinical hematology procedures. Specific blood cell measurements that are made by these procedures include white blood cell count (WBC), red blood cell count (RBC), hematocrit (HCT) hemoglobin content (Hgb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MHC) and platelet parameters such as platelet count. The function of a hematology control product is to provide a means of ascertaining the accuracy and precision of the instrument used to make these specific blood cell measurements.
Hematology control products for the above clinical hematology procedures are known. In these prior art products, a blood cell analog having known attributes is prepared from human or animal cells, or synthetic particles, such as latex, and maintained in an aqueous suspension to simulate human blood. Typically, the control products are required to be stored at a temperature between about 2.degree. C. and 8.degree. C. If the control product exceeds this temperature range, the product will not be suitable as a hematology control product because of product deterioration. Usually, stabilized red blood cells re used to simulate red blood cells in whole blood and fixed white or red lood cells are used to simulate white blood cells in whole blood.
With the numerous types of automatic hematology instruments for particle counting now available, quality control using hematology control products is necessary since the possibility of malfunctioning of the instrument is ever present. Although this disclosure will be directed primarily to embodiments involving the use of automated hematology instruments of the Coulter type, as exemplified by U.S. Pat. Nos. 2,656,508 and 3,502,974. It should be understood that the hematology control product and the method of use described herein finds wide application with hematology instruments generally. Accordingly, the term "automated hematology instrument" as used herein, should be understood to include, in addition to Coulter type hematology instruments, any other type of automated hematology instrument which discriminates among particles by the use of measurements of direct current (DC) resistance, radio frequency (RF) resistance, absorbance, light scatter, fluorescence and combinations thereof.
Automated hematology instruments are now being widely used in developing countries. However, many of these countries lack adequate controlled temperature shipping and storage facilities. The lack of such facilities has presented special problems for hematology control products. Typically, the control products require controlled shipping temperatures to remain useful by the time when the customer receives it. More specifically, if the control product freezes and thaws during shipping or is subjected to temperatures greater than 10.degree. C., the control product will deteriorate and will not work for quality control purposes. The freeze and thaw causes the red blood cells, white blood cells and platelets, or analogs thereof, to change in size or to lyse, so that the control product is no longer useful for quality control measurements. Similarly, the elevated temperature causes the red blood cells, white blood cells and platelets, or analogs thereof, to either be destroyed or to change in size so that he control product is no longer useful for quality control measurements. In addition, the control product needs to have open vial stability, without refrigeration, because the laboratory might not ave sufficient refrigerated storage for the control product. More specifically, he commercial control product will rapidly deteriorate when not maintained at roper storage conditions, 2.degree. C. to 8.degree. C., making it unsuitable for quality control measurements. Consequently, there exists a need for a new hematology control product which is stable to shipping at extreme temperatures and which has an extended product stability. The hematology control product is used to monitor automatic hematology instrument performance and to aid the customer in the repair of the unit on site with minimal service representative intervention.